Synthetic resin film bag having valve for preventing free leakage

ABSTRACT

A synthetic resin film bag having a valved opening defined by a set of plied films sealed to a base film or sheet which forms the bag per se. The plied films consist of a long leg and a short leg, one edge of the short leg being heat sealed to the long leg, while the combination is in turn heat sealed to the base film or sheet. The base sheet or film is folded upon itself and sealed, the only opening remaining, for the filling operation, is the valved opening, such preventing any contents of the bag from easily escaping subsequent to completion of the filling operation. In addition, the valved opening further includes a slit or a plurality of apertures provided within an area of the long leg which is not heat sealed with respect to the short leg, such slit or apertures serving to perform the function of a pressure relief valve or as means to facilitate opening of the bag when desired after the bag has been filled with its contents.

United States Patent n91 Nishimura et al.

[ 51 Sept. 9, 1975 [75] Inventors: Makoto Nishimura, Tokyo; Hideo Fujii,Yokohama. both of Japan [73] Assignee: Toyo Soda Manufacturing Co.,Ltd., Yamaguchi, Japan [22] Filed: Mar. 20, 1974 [2l] Appl. No.: 453,054

Related U.S. Application Data [63] Continuation-impart of Ser. No,276,558, July 3|,

i972, abandoned,

2,838,225 6/l958 Carries et al. 229/625 3,102,676 9/[963 Danelli ct al.229/625 3,204,825 9/[965 Underwood 229/55 X 3,236,438 2/[966 Rhodes229/6245 3,322,327 5/1967 Prall 229/625 3,437,258 4/l969 Kugler l.229/58 Primary ExaminerGeorge E. Lowrance Assistant Examiner-Stephen P.Garbo Attorney, Agent, or Firm-Oblon, Fisher, Spivak,

McClelland & Maier [57] ABSTRACT A synthetic resin film bag having avalved opening defined by a set of plied films sealed to a base film orsheet which forms the bag per se. The plied films consist of a long legand a short leg, one edge of the short leg being heat sealed to the longleg, while the combination is in turn heat sealed to the base film orsheet. The base sheet or film is folded upon itself and sealed, the onlyopening remaining, for the filling operation, is the valved opening,such preventing any contents of the bag from easily escaping subsequentto completion of the filling operation. In addition, the valved openingfurther includes a slit or a plurality of apertures provided within anarea of the long leg which is not heat sealed with respect to the shortleg, such slit 0r apertures serving to perform the function of apressure relief valve or as means to facilitate opening of the bag whendesired after the bag has been filled with its contents,

8 Claims, [2 Drawing Figures PATENTEUSEP 9mm 3,904,107

sum 1 BF 3 FIG. 2

PATEHTED SEP 9 I975 SHEET 2 BF 3 FIG. 7

FIGJO SYNTHETIC RESIN FILM BAG HAVING VALVE FOR PREVENTING FREE LEAKAGECROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation-in-partapplication of application Ser. No. 276.558 filed July 3]. I972 nowabandoned.

BACKGROUND OF THE INVENTION l. Field of the Invention The presentinvention relates generally to synthetic resin film bags and moreparticularly to a flexible synthetic resin film bag having a valvedopening for preventing leakage of the contents of the bag without thenecessity of expressly sealing the opening.

2. Description of the Prior Art Conventional synthetic resin film bagsare scaled after being filled with contents through one side of the bag.the scaling of the opening of such a bag being done by heatsealing sincethe base film is normally made of a thermoplastic resin. However. whenthe contents are filled via such an opening in the bag. the contents adhere to the inner surfaces of the opening causing the heat-sealing ofsuch opening to be difficult to complete.

In order to obviate this problem. other conventional synthetic resinfilm bags have employed valves which need not be heat sealed in order toprevent leakage of the bag contents therefrom under normal conditions.However. if excess pressure builds up within the bag. either within ashort period of time or over an extended period of time. suchconventional valves tend to be blown open whereupon the contents of thebag may become discharged therefrom.

Still further, although such conventional valves facilitate the fillingoperation associated with the bags and the closing of such bags. it issometimes difficult to open such bags when desired due to the presenceof the contents therewithin relative to the location of the bag valvemeans.

SUMMARY OF THE INVENTION Accordingly. it is an object of the presentinvention to provide an improved synthcthic resin film bag.

Another object of the present invention is to provide an improvedsynthetic resin film bag which can be simply and continuously prepared.

Still another object of the present invention is to pro vide an improvedsynthetic resin film bag which has a valved opening to prevent leakageof the contents therefrom without the necessity of expressly sealing theopening subsequent to the filling operation.

Yet another object of the present invention is to provide an improvedsynthetic resin film bag which has a valved opening which will preventthe contents of the bag from being expelled therefrom even underpressure conditions.

A further object of the present invention is to provide an improvedsynthetic resin film bag which has a valved opening which willfacilitate opening of the bag when desired after such bag has beenfilled with particular contents.

The foregoing objectives are achieved according to this inventionthrough the provision of a synthetic resin film bag made of a flexiblebase film or sheet having a valved opening defining an entrance portformed by a base film or sheet and a set of plied films consisting of along leg and a short leg. wherein one end of the short leg is sealedupon the long leg. and both sides edges of the plied films are heatsealed to the base film. by a mass production process. therebypreventing any con' tents of the bag from easily escaping. A slit or aplurality of apertures are also provided within an area of the long legwhich is not heat sealed with respect to the short leg. such slit orapertures serving to perform the function of a pressure relief valve oras means to facilitate opening of the bag when desired after the bag hasbeen filled with its contents.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects. features. andattendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detaileddescription when considered in connection with the accompanyingdrawings. in which like reference characters designate like orcorresponding parts throughout the several views. and wherein:

FIG. I is a perspective view. partly in cross-section. of one embodimentof the bag constructed according to this invention;

FIG. 2 is an enlarged view of the valve opening of the bag illustratedin FIG. 1;

FIG. 3 is a view ofthc valve used in the present invention showing itscooperative parts before being sealed to the bag per se;

FIG. 4 is another view ofthe valve illustrated in FIG. 3 in an expandedcondition, as it would be during the bag filling process.

FIG. 5 is a sectional view of the bag as illustrated in FIG. 1. takenalong line AA' of FIG. 1'.

FIG. 6 is a sectional view of the bag as illustrated in FIG. 1. takenalong the line 3-8 of FIG. 1;

FIG. 7 is a sectional view of the bag as illustrated in FIG. I, takenalong line CC' of FIG. 1'.

FIG. 8 is an enlarged sectional view of the bag as illustrated in FIG.I. taken along line AA' of FIG. I. wherein the bag is filled with packedmaterial and shows the condition of the opening of the bag when filled;

FIG. 9 is a view of another embodiment of the valve utilized in thepresent invention, showing its cooperative parts before being sealed tothe bag per sc'.

FIG. 10 is a view of still another embodiment of the valve utilized inthe present invention. showing its eooperative parts before being sealedto the bag per se;

FIG. 11 is a view of a further embodiment of the valve utilized in thepresent invention. showing its eooperative parts before being sealed tothe bag per se; and

FIG. 12 is a view similar to that of FIG. 8 illustrating the function ofthe slits within the valve of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to thedrawings. and more particularly to FIGS. 1 and 3 thereof. the syntheticresin film bag I of the present invention is folded over and sealedalong its ends II and II. as well as its side 12 except for a regiondefining opening 2. Within the opening 2. there is fixed a set offlexible synthetic resin plied films 3. and as shown in FIG. 3, theplied films 3 can be formed from two flexible sheets consisting of along leg 3' and a short leg 3". One end 7 of the short leg 3" is heatsealed to the long leg 3' so as to form a set of overlapping pliedfilms. while both longitudinal side edges, or in other words. those sideedges extending parallel to the central axis of the opening 2. of theset of plied films 3 are in turn heat sealed to one of the innersurfaces of the folded base film or sheet comprising bag 1.

Referring particularly to FIG. I. the plied films 3 may first be fixedto one of the inner surfaces of bag 1 at only its lower edge 4. whilethe upper edge 4 of the plied films 3 may be fixed to the inner surfacesof both base films or sheets which form the bag per sc. The ends of thebase films are then heat-sealed to form the heat-sealed end 11. The basefilm thickness for making a bag ranges from l/lOOmm to lmm.

Referring particularly to FIG. 2. the plied films 3 may alternatively befixed to only one of the base films l at its upper edge 4 and its loweredge 4'. so that the opening 2 is displaced relative to that sheet orbase film of the bag. In either case. the plied films 3 for the opening2 is fixed to at least one of the base films I at both the upper andlower edges 4, 4' respectively. such that the short leg 3" is within thelong leg 3' and within opening 2.

The bag I including the valve opening 2 consisting of the base film andthe plied films 3 is then cut and heatsealed to a specific size. theedge 12 of the base films being fixed relative to the end of the valveopening 2 such that the inner surface of one of the base films I isfixed to one surface of the long leg 3'. along the line 6 (see FIGS. and8) thereby forming a bag which is completely enclosed and sealed exceptfor the portion defining valve opening 2.

Referring now to FIGS. 7 and 8, the valve action may be described.Flowablc material is fed through the opening 2 of the plied films. Asthe plied films 3 may be fixed upon the inner surface of one base film.only, the plied films are pressed toward that one inner surface of thebase film by the contents of the bag thereby serving to close theopening of the bag. Even though the contents flow between the long leg 3and the base film. leakage is prevented by the contact of the short leg.with the long leg. as well as with the base film I. The invention thusprovides a double valve effect due to the action of the long and shortlegs of the plied films.

The synthetic resin used in manufacturing the bag of the presentinvention may be for example, polyethylenc; polypropylene;polyvinylchloridc; nylon; vinylcster copolymers. such as. for example. acopolymer of ethylele and vinylacctate; or any other polymers andcopolymers capable of forming flexible films. It is also possible to usecomplex films made of a synthetic resin film laminated with paper.aluminium foil, fabric or other sheets.

The valve opening 2 is usually located at an upper corner of the bag 1,although it is possible to form the opening at any portion along a seamof the bag if required. It is usual to make the plied films from a moreflexible film than that of the base film of the bag in order to make thevalve action more effective. A thick ness of l/l00mm to 1mm is used forthe base film.

The difference in length between the longer leg and the shorter legdepends upon the nature of the contents of the bag. When the length ofthe long leg is increased compared to the width of the opening anytendency for leakage from the bag is decreased but problems may arise inthe filling operation. Accordingly. the length of the long leg is thusdetermined by such considerations. Where the bag is used for the packageof powder. granules. grain. liquid. and gas, it is preferable that thelength of the longer leg be approximately equal to the width of theopening or longer. while the length of the short leg should exceedone-fourth. and preferably be about four-fifths. the length of the longleg. For example. in packing granules, such as. for example. granularfertilizer it is preferable that the difference of lengths between thelong and short legs be about 50 mm when the width of the opening is [40mm (the thickness of the plied films being about mm). The length of thelong leg should thus be longer than the width of the opening mm), for ifthe length of the long leg is shorter than the width of the opening. thetendency towards leakage is increased.

Where the bag is used for carrying powder, it is preferable to increasethe difference of lengths between long and shorter legs by increasingthe length of the long leg. On the other hand. where a liquid such aswater is packed, the width of the opening is decreased and the length ofthe long leg is increased. Where the contents are fine particles and ahigh efficiency valve is required, the long leg 3' of the plied filmscan be made of two pieces of flexible film. the pieces being of equal orunequal length. In the instance where unequal length pieces areutilized. the longer piece will nevertheless be of such length so as tooverlap the short leg 3" of the plied films.

When the powder. granules. grain. liquid and gas is to be removed fromthe bag. the valve 2 can be easily opened by providing an elongated slit8 upon the long leg 3. as seen in FIG. 9. The slit 8 is formed upon anarea of the long leg 3' which is not heat sealed with re spect to theshort leg 3". In lieu of the slit 8. it is also possible to provide aline comprised ofa plurality of linear apertures 8 as seen in FIG. I0,by which the line may be broken so as to form a single elongated slitwhen the bag is packed, transferred or handled. and when the valve isdesired to be opened for removing the contents therefrom. As may also beseen from FIG. II. another embodiment of the valve may include V shapedslits 8 serially disposed within a line extending along the width of thelong leg 3'.

The function of the valve slits 8 can be readily appreciated withparticular reference to FIG. 12. After the bag has been filled with anyone of its particular type contents. should the bag be subjected to aforce. such as that denoted by and applied thereto in the direction F.as might occur during shipping and handling thereof, the surface of thebag upon which the force is impressed will of course be depressedtending to laterally expand the bag in reaction thereto. Within aconventionally valved bag. such reaction would tend to expel the bagcontents out of the bag past the valve members 3' and 3". leakagethereby resulting.

With the valve of the present invention however. due to the presence ofthe slits 8 provided within the long leg member 3'. a flow pattern. asdenoted by the arrows. is set up within the bag contents in response tothe application of force F whereupon in lieu of the contents beingforced out of the bag past the valve members 3' and 3". the contents ofthe bag interposed. for example. between the short leg member 3" and thelong leg member 3'. will be forced through the slits 8 and into the mainportion of the bag. the valve thereby acting as a pressure relief valvewhereupon leakage from the bag is substantially prevented or reduced.

Similarly, the valve facilitates opening of the bag when it is desiredto remove the contents therefrom. When for example. means are insertedwithin the valve opening 2 so as to open the valve means. the short legmember 3" will be pushed inwardly toward the long leg member 3'whereupon the bag contents interposed. for example. between the legmembers will again be forced through the slits 8 and into the mainportion of the bag. Without such slits, opening of conventionally valvedbags has been substantially difficult.

There have been various difficulties encountered in mass producing thebags having the described structure. One ofthe difficulties is to fixthe appropriate surfaces of the base films to the appropriate surfacesof the plied films without sealing the inner surfaces of the long leg 3.so as to thereby close opening 2. In the heat sealing operation, anon-adhering insert such as cellophane or paper-aluminium foil can beinserted within the opening to overcome this problem. However, thismethod may lead to disadvantages in the form of low efficiency andvariable quality of production.

According to the improved operation of the present invention. the innersurfaces of the prefabricated plied films are coated with non-adhesivematerial so as not to adhere to each other in the heat sealing process.Such material may also be coated upon the base film of bag 1 in theregion of opening 2. The non-adhesive material may be polyamide; across-linked rubber; or a polymer having a high melting point such as.for example, cellulose nitrate, ink, paint containing an inorganic orheat resistant pigment, and silicon oil. It has been found that the useof printing ink containing such a non-adhesive material is preferred.

In production, the coated prefabricated plied films are automaticallyadjusted to the edge line of the inner surface of the base film of thebag which is continuously supplied, and then heat sealed to it at theappropriate positions as discussed heretofore. The base film is thenbeat cut, and folded so as to form a bag. adhering the end of the basefilm corresponding to the edge 12 (see FIG. 2) of the bag 1 with anadhesive composition, and sealed at the top and bottom edges of the bag,the edges of the bag being continuously heat sealed by a belt type heatsealer. The adhesive composition may be one having affinity to the basefilm, such as for example. a melt of low density of polyethylene; or acopolymer of ethylele, such as. for example, ethylene vinylacetatecopolymer; or a hot melt adhesive prepared by admixing low densitypolyethylene with an ethylenevinylacetate copolymer and a modifier. Themodifiers may be, for example. wood resins. tall oil rosins, alphapinene rosins, maleie acids, hardened rosins, cumaroneindene rosins.polystyrene resins having a l25C softening point, ketone resins.cumarone resins. non-reactive phenolic resins, dibutylphthalate terpeneresins and B-pinene resins. or the like.

The invention is further illustrated by the following examples:

EXAMPLE I A bag 440 mm in width and 540 mm in length was prepared byusing a film having a 0.20 mm thickness made from a copolymer ofethylene and vinylacetate containing about 5% by weight a vinylacetatecomponent. A set of plied films. consisting of two films. for

long and short legs respectively. was used and was fixed upon the innersurface of the base film of the bag. The short leg of the plied filmswas a film mm in length and mm in width. while the long leg of the pliedfilms was a film 120 mm in length and [30 mm in width. The film for theplied films was of the same material as the base film of the bag, butonly 0. l5 mm in thickness.

Non-adhesive material was coated upon the inner surface of the short legat the end of the plied films in a strip 20 mm in length and 100 mm inwidth. such strips being positioned 15 mm from those portionscorresponding to the upper and lower parts of the opening. Thenon-adhesive material used was Glavia ink for polyethylene printing(Type PKH-39l Blue manufactured by Toyo lnk Mfg. C.) and was coated to athickness about two or three times the thickness of the film.

The long leg and the short leg were presealed to form the plied films,and the end of the plied films was adjusted to the edge of the base filmof the bag. the plied films then being heat-sealed at its upper andlower edges 4 and 4' respectively. the width of the sealing edges being15 mm. Accordingly. the width of the opening of the plied films was lUUmm. The top and bottom parts of the base film of the bag wererespectively heat cut and sealed. while the edge having the plied filmswas heat sealed by a belt type heat sealer to continuously prepare thebag. The opening could be easily opened and a nozzle of a packagingmachine was inserted without trouble. Twenty-five kg of calcium silicatepowder for fertilizer was packed within the bag and the bag was thendropped from a height of 2.5 m. Leakage of the contents was thenmeasured. Such measurements were carried out for five such drop testswith the opening facing the ground. and subsequently for five drop testswith the opening facing upwards.

The results are shown in Table I.

A bag 460 mm in width and 650 mm in length using a base film 0.20 mm inthickness. made of the same material as was used in Example I, wascontinuously prepared. The film for the plied films consisted of a longleg [50 mm in length and a short leg 100 mm in length. both being [55 mmin width, while the width of the opening was I25 mm. (thickness of pliedfilms being about 80 mm).

Low density polyethylene having a density of 0.917 g/cc and a Melt Indexof 6 g/IO min. was melt-extruded at C from an extruder in order toadhere together the end of the bag 1 consisting of the outer surface ofthe long leg 3 and an inner surface of the base film, the bag beingcontinuously prepared. Twenty-five kg of crystalline ammonium chloridefor fertilizer having 2 3 mm particle diameter was then packed withinthe bag.

TABLE 2 Sample Amount of leakage \vith Sample plied films facing downAmount of leakage with plied films facing up A l) g D (I g B t) g E (l gC g F g Leakage is highest where the tube is fixed to the bottom of thebag.

EXAMPLE 3 A bag 400 mm in width and 400 mm in length. using a film 0.1 8mm in thickness and made of polyethylene. was prepared by a highpressure method. the bag having a melt flow index of 0.6 and a densityof 0.9l9 g/cc. Plied films mm in width were utilized. the long leg being70 mm in length while the short leg was mm in length such legs beingfixed to the side of the bag in accordance with Example 1. 4.5 k ofwater was inserted into the bag and three such bags were stacked andkept for 10 days. No leakage of water was found. In further test. airwas inserted into the bag and a weight of 70 kg placed upon the bag.After a full day. no leakage of air was found to have occurred.

Thus. it may be seen from the above. that the synthctic film bag of thepresent invention has important advantages over the known prior artstructures in that complete effective sealing can be obtained withoutactually scaling the opening of the bag by the use of conventionalmethods. such as. for example. heat-sealing. with its attendantdrawbacks. Moreover. the structures of the valve is relatively simple.and can be easily and automatically prepared Obviously. manymodifications and variations of the present invention are possible inlight of the above teachings. It is to be understood therefore. thatwithin the scope of the appended claims the present invention may bepracticed otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A bag made of a flexible base film or sheet comprising:

a valved opening having an entrance port defined by said base film orsheet and a set of plied films consisting of a long leg and a short leg;

wherein one end of said short leg is sealed upon said long leg withinsaid valved opening, one end of said long leg is sealed to said basefilm at said entrance port. and the longitudinal side edges of said setof plied films are heat sealed to said base film. thereby preventing anycontents of said bag from easily escaping; and

wherein further at least one slit means is provided within said long legat a region which is not heat sealed with respect to said short leg forfacilitating opening of said valve and removal of the contents from saidbag. and for relieving excess pressures within said bag.

2. A bag as set forth in claim I, wherein one end of said short leg issealed to one end of said long leg while the opposite end of said shortleg is freely movable relative to the opposite end of said long log 3. Abag as set forth in claim 1. wherein the length of said short leg ofsaid set of plied films is not less than one-quarter of the length ofsaid long leg.

4. A bag as set forth in claim 1. wherein said set of plied films isformed by two unequal lengths of flexible film or sheet and sealed tosaid base film or sheet along two opposite edges.

5. A bag as set forth in claim 1, wherein the inner sur faces of saidvalved opening are coated with nonadhesive material thereby preventingthe sealing of said valved opening when the periphery of said bag issealed.

6. A bag as set forth in claim 1. wherein a plurality of slits areprovided within said long leg.

7. A bag as set forth in claim 6. wherein said slits are linearlyconfigured.

8. A bag as set forth in claim 6, wherein said slits are Vshaped.

1. A bag made of a flexible base film or sheet comprising: a valvedopening having an entrance port defined by said base film or sheet and aset of plied films consisting of a long leg and a short leg; wherein oneend of said short leg is sealed upon said long leg within said valvedopening, one end of said long leg is sealed to said base film at saidentrance port, and the longitudinal side edges of said set of pliedfilms are heat sealed to said base film, thereby preventing any contentsof said bag from easily escaping; and wherein further at least one slitmeans is provided within said long leg at a region which is not heatsealed with respect to said short leg for facilitating opening of saidvalve and removal of the contents from said bag, and for relievingexcess pressures within said bag.
 2. A bag as set forth in claim 1,wherein one end of said short leg is sealed to one end of said long legwhile the opposite end of said short leg is freely movable relative tothe opposite end of said long leg.
 3. A bag as set forth in claim 1,wherein the length of said short leg of said set of plied films is notless than one-quarter of the length of said long leg.
 4. A bag as setforth in claim 1, wherein said set of plied films is formed by twounequal lengths of flexible film or sheet and sealed to said base filmor sheet along two opposite edges.
 5. A bag as set forth in claim 1,wherein the inner surfaces of said valved opening are coated withnon-adhesive material thereby preventing the sealing of said valvedopening when the periphery of said bag is sealed.
 6. A bag as set forthin claim 1, wherein a plurality of slits are provided within said longleg.
 7. A bag as set forth in claim 6, wherein said slits are linearlyconfigured.
 8. A bag as set forth in claim 6, wherein said slits areV-shaped.